1. Technical Field of the Invention
The present invention relates to a multiple disc friction clutch and a motor cycle therewith.
2. Description of Related Prior Art
Generally, a multiple disc friction clutch is provided with a clutch outer member for taking in or inputting a power from an engine side, and a clutch hub for taking out or outputting the power from the clutch to a rotating member, and is structured such that a plurality of input friction plates and output friction plates are arranged between the clutch outer member and the clutch hub, and the clutch is connected by pressing a pressing member onto the friction plates in an axial direction of the rotating member by means of a clutch spring. Further, the clutch is disconnected by moving the pressing member in the axial direction of the rotating member against the clutch spring by means of a release mechanism.
A pressing load of the pressing member against the friction plates is set by the clutch spring, however, is generally fixed to a constant value regardless of a change of an engine drive torque. Accordingly, in a small-sized clutch, a value of the pressing load is small and a clutch operating load on releasing becomes small in correspondence thereto, and in a large-sized clutch, the value of the pressing load is large and the clutch operating load on releasing becomes large in correspondence thereto (Japanese Unexamined Patent Publication No. 61-96222).
If the clutch operating load on releasing is increased as mentioned above in accordance with the enlargement in size of the clutch, a comfortableness of the clutch operation is lowered. Particularly, for a person who has less physical strength such as a woman, an elderly person, or the like, if the clutch operating load is large, a load applied to a wrist or a finger becomes large, and it is impossible to comfortably execute the clutch operation.
With respect to the multiple disc friction clutch in which the pressing load is fixed to the constant value, in order to reduce the clutch operating load, there has been developed a multiple disc friction clutch which can assist (increase) a clutch operating force by a hydraulic mechanism and can increase the pressing load. However, since it is necessary that the hydraulic mechanism is provided, a cost becomes higher as well as a parts number is increased.
An object of the present invention is to provide a multiple disc friction clutch mounted to a vehicle, such as a motor cycle or the like, in which it is possible to reduce a clutch operating load on releasing on the basis of a simple structure by utilizing an engine drive torque without requiring an expensive and complicated part such as the hydraulic mechanism or the like.
Another object of the present invention is to achieve a structure which can reduce a number of friction plates or downsize a diameter of the friction plate while maintaining a torque transmission capacity of the clutch, in a motor cycle or the like in which it is not necessary to reduce the clutch operating load.